Fix error with fused types and optional template params.
Fix error with fused types and optional template params.

fabianrost84/cython,c-blake/cython,scoder/cython,scoder/cython,scoder/cython,cython/cython,cython/cython,da-woods/cython,fabianrost84/cython,c-blake/cython,c-blake/cython,c-blake/cython,fabianrost84/cython,c-blake/cython,scoder/cython,fabianrost84/cython,fabianrost84/cython,da-woods/cython,ChristopherHogan/cython,da-woods/cython,ChristopherHogan/cython,cython/cython,ChristopherHogan/cython,cython/cython,da-woods/cython